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Registered: ‎12-27-2016

Difference between OverTempPowerDown and XADCPowerDown

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Hi,

 

I can't figure out what is the difference between those two parameters (from UG628):

 

OverTempPowerDown

 

XADCPowerDown

 

The OverTempPowerDown is also present in the UG908. Does it mean that XADCPowerDown is deprecated.

 

OverTempPowerDown_Zynq7000

 

Moreover, it is only present in the Zynq-7000 sub-chapter, not in the 7-Series.  Why ?

 

Thanks,

Nicolas Mariotti

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Moderator
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Registered: ‎04-18-2011
XADCPowerDown is intended to power off the XADC. When it is not instantiated it rubs in default sequencer mode so it will consume some power.
There are power down bits on the block so I guess this is for shutting it off when you don't Instantiate it.

Over temperature shut down is meant to shut down the FPGA design. It goes back to the start. The GTS Is asseted GHIGH AND GWE are both deasserted and it waits for the temperature to drop under the ot lower setting. At this point it re-does the start up state machine that runs at the end of config and the design comes back up
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Scholar
Scholar
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Registered: ‎02-27-2008

when the device has a XADC,

You may use it to set an over temperature alarm.  Then you have to do something about it (like shut off the power, remove the clock, etc.)

 

The device cannot turn its power off internally itself.  But it will clear configuration:

 

https://forums.xilinx.com/t5/Welcome-Join/how-can-i-provide-Thermal-Shutdown-Feature-for-7-series-FPGAs/td-p/682226

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
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Registered: ‎04-18-2011
XADCPowerDown is intended to power off the XADC. When it is not instantiated it rubs in default sequencer mode so it will consume some power.
There are power down bits on the block so I guess this is for shutting it off when you don't Instantiate it.

Over temperature shut down is meant to shut down the FPGA design. It goes back to the start. The GTS Is asseted GHIGH AND GWE are both deasserted and it waits for the temperature to drop under the ot lower setting. At this point it re-does the start up state machine that runs at the end of config and the design comes back up
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Scholar
Scholar
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Registered: ‎02-27-2008

I was unaware you could power down the XADC,

 

Now I know.

 

Thank you,

Austin Lesea
Principal Engineer
Xilinx San Jose
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@austin no problem.

Very small power saving but you can turn it off either via the drp port if you instantiate it in your design or via the bitstream settings.
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Registered: ‎12-27-2016
Thanks,

I understand now. But why does the XADCPowerDown description mention "over-temperature shutdown" which is quite misleading ?
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Scholar
Scholar
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Registered: ‎02-27-2008

n,

 

The XADC may be used to trigger an alarm, and provide a signal.  What you do with it is, of course, up to you.  As with all 'features' it is programmable.  That the control of the power is not on the device (must be external) is detailed in the documents.

 

As with all marketing, an engineer needs to read the data sheet and user guides to wade through hyperbole ...

Austin Lesea
Principal Engineer
Xilinx San Jose